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United States Patent |
5,290,273
|
Tan
|
*
March 1, 1994
|
Laser treatment method for removing pigement containing lesions from the
skin of a living human
Abstract
A laser treatment method is provided which removes pigment containing
lesions, both normal and abnormal medically, from the skin of a living
human. The methodology comprises a carefully controlled irradiation of the
chosen treatment site on the skin of a living human; avoids the creation
of cosmetically disfiguring scars; and eliminates the typical
hypopigmentation as well as the pitting and other changes in skin texture
normally accompanying conventionally known laser treatment techniques.
Inventors:
|
Tan; Oon T. (1 Marlborough St., Boston, MA 02116)
|
[*] Notice: |
The portion of the term of this patent subsequent to June 8, 2010
has been disclaimed. |
Appl. No.:
|
066875 |
Filed:
|
May 25, 1993 |
Current U.S. Class: |
606/9; 128/898; 606/2; 606/3; 606/13 |
Intern'l Class: |
A61B 017/36 |
Field of Search: |
128/878
606/3,2,9,13
|
References Cited
U.S. Patent Documents
4316467 | Feb., 1982 | Muckerheide | 606/9.
|
4718416 | Jan., 1988 | Nanumi | 606/9.
|
4854320 | Aug., 1989 | Dew | 606/9.
|
5000752 | Mar., 1991 | Hosrin et al. | 606/9.
|
5057104 | Oct., 1991 | Chess | 606/9.
|
5059192 | Oct., 1991 | Zaias | 606/9.
|
5217455 | May., 1993 | Tan | 606/9.
|
Primary Examiner: Aschenbrenner; Peter A.
Attorney, Agent or Firm: Prashker; David
Parent Case Text
CROSS-REFERENCE
This application is a Continuation-In-Part of U.S. patent application Ser.
No. 743,797 filed Aug. 12, 1991, now U.S. Pat. No. 5,217,455.
Claims
What I claim is:
1. A laser treatment method for removing pigment containing lesions from
the skin of a living human, said method comprising the steps of:
irradiating on a first occasion a chosen treatment site on the skin of a
living subject of about 1-100 millimeters in diameter with a beam of
pulsed light from a laser delivery system, said pulsed light having a
wavelength from about 700-1,100 nanometers, fluences of about 1-50 Joules
per square centimeter, and a pulse duration of about 1-300 nanoseconds;
maintaining said irradiation to disrupt at least one pigment containing
lesion on the chosen treatment site on the skin of the living human until
a color change endpoint on the skin surface is achieved by said laser
light treatment while largely avoiding the destruction of normal skin
structures and cells;
allowing the skin at said irradiated treatment site to heal for a time
period not less than about 7 days and not more than about 70 days; and
then
irradiating on at least one subsequent occasion the chosen treatment site
on the skin of the living human with another pulsed beam of laser light
having a wavelength from about 700-1,100 nanometers, fluences of about
1-50 Joules per square centimeter, and a pulse duration of about 1-300
nanoseconds, said subsequent irradiation occasion being repeated as
necessary to achieve substantial clearance of the chosen treatment site on
the skin.
2. A laser treatment method for removing pigment containing lesions from
the skin of a living human, said method comprising the steps of:
irradiating on a first occasion a chosen treatment site on the skin of a
living subject of about 1-100 millimeters in diameter with a beam of
pulsed light from a laser delivery system, said pulsed light having a
wavelength from about 700-1,100 nanometers, fluences of about 1-50 Joules
per square centimeter, and a pulse duration of about 1-300 nanoseconds;
maintaining said irradiation to disrupt at least one pigment containing
lesion on the chosen treatment site on the skin of the living human until
a color change endpoint on the skin surface is achieved by said laser
light treatment while largely avoiding the destruction of normal skin
structures and cells;
allowing the skin at said irradiated treatment site to heal for a time
period not less than about 7 days and not more than about 70 days; and
then
irradiating on multiple subsequent occasions the chosen treatment site on
the skin of the living human with another pulsed beam on laser light
having a wavelength from about 700-1,100 nanometers, fluences of about
1-50 Joules per square centimeter, and a pulse duration of about 1-300
nanoseconds, said subsequent irradiation occasion being repeated as
necessary to achieve substantial clearance of the chosen treatment site on
the skin.
3. The laser treatment method as recited in claim 1 or 2 wherein said
irradiation of the chosen treatment site on the skin is controlled to
avoid causing whiteness and pitting of the skin.
4. The laser treatment method as recited in claim 1 or 2 wherein said
irradiation on the first occasion employs a lesser fluence value than said
irradiation on said second occasion.
5. The laser treatment method as recited in claim 1 or 2 wherein said
irradiation on said first occasion employs a greater fluence value than
said irradiation on the second occasion.
6. The laser treatment method as recited in claim 1 or 2 wherein said
irradiation employs laser light having a wavelength of from 750-800
nanometers.
7. The laser treatment method as recited in claim 1 or 2 further comprising
applying a topical antibiotic preparation to the chosen treatment site on
the skin after each irradiation occasion.
Description
FIELD OF THE INVENTION
The present invention is directed to a method for removing pigmentations,
lesions, and abnormalities from the skin of a living human using light
from a laser and its delivery system; and is particularly directed to the
use of the Alexandrite laser apparatus under carefully controlled
conditions for the removal of epidermal and dermal tissues as occurs both
in nature and by intervention.
BACKGROUND OF THE INVENTION
Among the more common conditions shared by humans generally is the presence
of lesions on the skin, many of which contain pigments in one or more
colors and some of which are considered abnormal although not always
dangerous to the individual. Typical examples of naturally occurring
pigmentations include freckles; age or liver spots; birthmarks; malignant
melanomas; nevi (melanocytic, epidermal, vascular, and connective tissue);
and lentigines (brown spots on the skin or mucous membrane). In addition,
a person's skin may have discoloring abnormalities due to vascular lesions
which are caused by an abundance of enlarged blood vessels. Common
examples of discolorful vascular lesions are "port wine" stain birth
marks; telangiectasis, a colored spot formed most commonly on the skin by
a dilated capillary or other small blood vessel; and hemangioma, a highly
visible benign tumor composed of well-formed blood vessels and classified
as capillary or cavernous.
In comparison, intervention created pigment containing lesions are commonly
called "tattoos" and are commonly divided into two different categories:
human-caused tattoos and traumatic-inflicted tattoos. Traumatic-inflicted
tattoos are created typically as a result of accidents or other mishaps
which cause scrapes, abrasions, explosion, or lacerations in a manner such
that foreign material inadvertently becomes embedded into the skin. During
the healing process, the skin becomes pigmented and often scarred as a
result. In comparison, human-created tattoos are a popular form of skin
decoration and self-expression in many cultures and societies. A common
example here in the U.S. is the tattooed sailor; and it has been estimated
that as many as 10% of the U.S. general population have tattoos somewhere
on the skin of their bodies.
It will be recognized and appreciated that many persons at some point in
their lives wish to remove pigment containing lesions, whether normal or
abnormal, from their skin for health and/or cosmetic reasons. Even those
individuals who voluntarily choose to create pigmented patterns on their
skin may subsequently in their lives choose to undergo treatment designed
to remove the pigmented lesion--often because of advancing age, or via a
change in lifestyle, or as a consequence of a new personal relationship.
Presently existing modes of removal treatment may achieve some clearing or
lightening of pigment containing skin areas but only at substantial risk
to the individual because of severe changes to the natural pigmentation
and coloring of the skin or by incurring actual scarring of the treated
skin area. The risks and severity of the multiple problems and
consequences associated with removing pigmentations and other lesions
generally of the skin is represented and illustrated by the difficulties
of removing tattoos. However, it is explicitly understood that tattoos are
merely one prototypic example of the different pigment containing lesions
known which require removal.
As is the circumstance with many kinds of pigment containing lesions, the
pigment lies inside the skin (i.e., the dermis or epidermis) and
destructive modes of treatment have been employed conventionally to remove
this pigment. Thus, a major problem of known treatments has been access to
the epidermal or dermal pigment; and the only way it has been possible to
remove the pigment(s) without using laser apparatus has been to remove all
the skin around the pigmented lesion from the most exterior surface
downwards into the deep tissues.
The conventional modes of treatment used for removal of pigmented lesions
generally thus presently include: surgical excision and skin graft;
dermabrasion; saliabrasion; cryosurgery; and laser light generated by
CO.sub.2, argon, Nd:YAG, and ruby lasers [Hirshowitz, D. E., Plast.
Reconstr. Surg. 373-378 (1980); Scutt, R. W. B., Br. J. Hosp. Med. J.
8:195 (1972); Manchester, G. H., Curtis 7:295 (1971); Clabaugh, F. M.,
Plast. Reconstr. Surg. 55:401 (1975); McDowell, F., Plast. Reconstr. Surg.
53:580 (1974); and Groot et al., J. Am. Acad. Dermatol. 15:518-522
(1986)]. While each of these modes of treatment has its own committed
group of adherents, practitioners, and supporters, all of them
unfortunately create as many problems as they cure concomitant with using
the conventionally known procedures.
For example, a well recognized problem and drawback with some presently
known laser treatment methods is that these routinely cause damage to both
pigmented and non-pigment cells in the skin without discriminating between
them. Laser treatment of pigment containing skin lesions has varied
markedly from merely the superficial to extreme depth in the skin with
little attempt to control the kind or the amount of tissue and cells
destroyed. Moreover, some laser treatment processes known to date almost
always cause a major change in skin texture; the skin is thus
substantially altered from being smooth, elastic, and mobile to being hard
and immobile and to becoming bumpy, cratered, or even pitted. In addition,
conventional laser treatments cause a loss of the normal skin markings
(normal ridges and valleys) as well as changes in normal skin pigmentation
(losses as well as increases in normal skin color). Therefore, the
resulting change in skin texture is almost always accompanied by a
consequential change in skin color in which the skin at the treated site
is no longer normal in pigmentation. Instead, the treated skin site
appears either porcelain-white or mottled with dark pigment, both of these
conditions resulting from either loss of all pigment or the implanting of
pigment in the dermis instead of the epidermis. All of these radical and
undesirable consequences and changes result from extensive, severe damage
induced by the presently known laser treatment modalities and treatment
methods.
Even the ruby laser (the best of the conventionally used laser systems) and
the known procedures using the ruby laser have been demonstrated to be
flawed, deficient, and inefficient for removing pigmentations, lesions,
and abnormalities from the skin of a living human. As has well been
described in the art, there are many problems and deficiencies concomitant
with or caused by the ruby laser system and its various modes of use. In
one mode, the ruby laser emits its laser light pulses called a normal
pulse Another known way to operate and use the ruby laser is in the
Q-switched mode; short bursts of pulses are emitted called a pulse train.
A pulse train becomes problematic when the pulses are of low power. When
this occurs, provided the pulses are discharged frequently enough and in
spite of the short pulses being in the nanosecond range, the effect on the
living tissue is similar to that of a continuous wave (CW) laser, which
produces a highly indiscriminate effect. Moreover, instead of destroying
the targeted structure with each pulse and, because the ruby energy output
is low, there is only sufficient energy to partially alter the pigment
containing lesion. Also, due to the characteristics of the ruby laser
itself, the intensity of each pulse burst can meaningfully vary and it is
very difficult for the practitioner to control the light energy dose
delivered to each laser exposed site.
In addition, there presently is no convenient or easy way of precisely
delivering the laser light beam to the patient. A common way of performing
this manipulation at present is by the use of an articulating arm which is
not only cumbersome but also easily goes out of alignment. This difficulty
results in a further decrease of laser energy available to destroy the
targeted tissue, thus making the ruby laser system even less efficient for
removing abnormal pigmentations. Also, when used in the non-Q switched
mode the ruby laser often produces severe scarring of the skin.
Another way to operate and use the ruby laser system conventionally is in
the Q-switched mode. In this alternative mode of use, a single energy
pulse of short duration (nanoseconds) is delivered to the skin by the ruby
laser. However, despite the usage of Q-switched ruby lasers in clinical
studies since the 1960's, the only currently available means of delivering
treatment energy pulses in this manner is again by means of an articulated
arm which is not only difficult to align and is bulky, but also creates
"hot spots" within the delivered light beam area. One reported study
revealed that multiple treatments using the ruby laser in the Q-switched
mode removed at least 90% of the normal coloration in the skin. Adverse
effects of hyper- and hypo-pigmentation were noted in some patients; and
pigmented lesion sites composed of colors other than blue-black were not
affected directly but instead showed a severe whitening of the skin as a
result of this treatment [Read et al., Br. J. Plast. Surg. 36:455-459
(1983)]. Another study [Taylor et al., Arch. Dermatol. 126:893-899 (
1990)] reported substantial lightening or total clearing of skin in 78% of
amateur tattoos and 23% of 13 professional tattoos. However, this report
demonstrated that multiple retreatments were required; transient
hypopigmentation was seen in 50% of treated skin sites; and notable
scarring appeared in approximately 6% of treated patients.
It is not surprising, therefore, that there is major interest in developing
new and improved laser delivery systems which may be used in a carefully
controlled method and treatment procedure for removing pigmentations from
the skin of a living human. It will be recognized and appreciated also
that while the development of new laser equipment and new laser delivery
systems constitutes one discrete area of technical research, such efforts
are meaningfully different and distinct from other investigations directed
to developing a clinical process and methodology under carefully
controlled operational parameters which would be effective and usable by a
dermatologist or other medical practitioner. Equally important, the
development of a clinically effective therapeutic treatment using a
carefully controlled laser apparatus and laser delivery system which would
prevent hypo-and/or hyperpigmentation as well as avoiding
cratering/pitting and elevation or destruction of dermal and/or epidermal
layers of the skin would be generally recognized as a major improvement
and advance by practicing dermatologist and clinicians treating patients
on a regular basis.
SUMMARY OF THE INVENTION
The present invention constitutes a laser treatment method for removing
pigment containing lesions from the skin of a living human, said method
comprising the steps of:
irradiating on a first occasion a chosen treatment site on the skin of a
living subject of about 1-100 millimeters in diameter with a beam of
pulsed light from a laser delivery system, said pulsed light having a
wavelength from about 700-1,100 nanometers, fluences of about 1-50 Joules
per square centimeter, and a pulse duration of about 1-300 nanoseconds;
maintaining said irradiation to disrupt at least one pigment containing
lesion on the chosen treatment site on the skin of the living human until
a color change endpoint on the skin surface is achieved by said laser
light treatment while largely avoiding the destruction of normal skin
structures and cells;
allowing the skin at said irradiated treatment site to heal for a time
period not less than about 7 days and not more than about 70 days; and
then
irradiating on at least one subsequent occasion the chosen treatment site
on the skin of the living human with another pulsed beam of laser light
having a wavelength from about 700-1,100 nanometers, fluences of about
1-50 Joules per square centimeter, and a pulse duration of about 1-300
nanoseconds, said subsequent irradiation occasion being repeated as
necessary to achieve substantial clearance of the chosen treatment site on
the skin.
BRIEF DESCRIPTION OF THE FIGURE
The present invention may be more easily and completely understood when
taken in conjunction with the accompanying drawing, in which:
FIG. 1 is an illustrative view of an unmodified Alexandrite laser
apparatus; and
FIG. 2 is a detailed view of the delivery system for the Alexandrite laser
apparatus of FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is a clinical treatment methodology to be used by
clinical dermatologists and other medical practitioners for the removal of
pigmentations, lesions, and abnormalities from the skin on a living human.
This treatment method employs a laser apparatus and a laser delivery
system having specified engineering capabilities able to provide carefully
controlled light wavelengths which can be directed at chosen treatment
sites on the skin of a living human. Since the methodology intrinsically
requires the existence and availability of a laser apparatus having
specified capabilities and engineering specifications, descriptive details
will be provided herein identifying at least one such laser apparatus
which can be modified to provide the specific operating parameters needed
in order to perform the treatment methodology efficiently and
successfully. Nevertheless, the treatment methodology comprising the
manipulative steps of the present invention are not dependent on one
particular type or class of laser equipment; and is not restricted to any
particular engineering specifications or apparatus designs as such. To the
contrary, the present treatment methodology is intended to be and is
capable of employing lasers of any type or capacity so long as the
specific parameters demanded by the treatment are provided in a
predictable and controlled manner. Hence, it will be clearly understood
that the present methodology is not dependent on any particular laser
equipment or system; and cannot be said to be an outgrowth or derivative
of any particular laser apparatus or laser system regardless of how such
technology was developed.
The present therapeutic treatment methodology is a dermatological technique
suitable for use generally in a variety of different clinical
applications. A representative, but non-exhaustive listing of applications
and uses for the treatment methodology are identified by Table 1 below.
TABLE 1
______________________________________
DERMATOLOGICAL APPLICATIONS AND USES
______________________________________
(i) Removal of tattoos (professional and non-professional):
(ii) Epidermal and dermal pigment(s) removal: The pigment in
these lesions can be either endogenous or exogenous. The
latter can be substances injected into the body which are
subsequently absorbed by specific structures in the skin and
enhances the absorption of the delivered laser light.
(iii)
Removal of melanin pigment from mucosae:
(iv) Ablation of skin: removal of skin tissue.
(v) Removal of superficial, benign, cutaneous, melanin
pigmented lesions:
(vi) Removal of foreign matter in the skin including endogenous
substances (such as calcium deposits) and exogenous matter
(such as lead, gravel, shrapnel, etc.):
(vii)
Removal of skin tumors, both benign and malignant
(such as epidermal nevus):
______________________________________
A number of major advantages and conveniences are provided by the present
treatment method. These include the following:
1. The present methodology is intended to be performed as a series of
repeated treatments spaced in time from each other at preselected
intervals as chosen by the physician with regard to the individual
responses of his patients. Each occasion for treatment (from first to
last) will provide an irradiation of the chosen treatment site on the skin
of the living human under carefully controlled conditions and include
treatment safeguards for exposure based upon the size, condition, and
health of the individual's skin. Thus, the therapeutic process is tailored
to the individual's particular response to each treatment and medical
status; is employed over defined skin areas in limited degree without
causing major destruction of the surrounding normal tissues and cells; and
provides for periods of skin healing within the planned cycles and timing
for the method from beginning to end.
2. The treatment method intends that the targeted treatment site on the
skin of the living human be exposed to carefully chosen wavelengths of
light energy, energy density, and exposure time. If the introductory
occasions of irradiation reveal themselves to be insufficient cumulatively
to achieve partial or substantial removal of the pigmentation, lesions, or
abnormality from the chosen skin site; then the timing, energy density,
and duration of light exposure can be increased or decreased incrementally
as needed on an individual basis until the intervention has been able to
achieve the desired goal of selective pigment removal. In this manner, the
personal health, safety, and cosmetic appearance of the skin are affected
only to the least extent required; and the side-effects of treatment such
as scarring or general disfigurement of skin tissues are minimized.
3. The present treatment process provides a means for delivering the laser
energy specifically to targeted zone alone. Because of the particular
laser parameters used, the laser light bypasses normal non-targeted skin
structures and cells. The methodology provides a means by which the
destruction of normal skin structures and cells is largely avoided,
eliminating loss of skin structures such as hair, sweat glands,
pigment-containing cells and the hardening of tissues at the treatment
site.
4. The present methodology also provides for a definitive color change at
the skin surface immediately following laser irradiation which serves as
an indicator that the correct treatment dose has been delivered to that
skin area. This is of paramount importance to the clinician. Firstly, the
clinician knows exactly the true location where the laser beam has been
delivered to the skin. Having such a definitive clinical endpoint on the
treated skin surface prevents the clinician from exposing the area to
multiple irradiations (i.e., summation of doses or even missing areas of
the lesion altogether). Secondly, the clinician is effectively informed by
the immediate color change whether the correct and sufficient dose of
laser energy has been delivered to the treatment site.
5. The present treatment method provides means of avoiding and eliminating
"whitening" or hypopigmentation as well as hyperpigmentation of the
skin--both of which have been the frequent and typical consequence of
previously known and conventionally employed laser treatment procedures.
The present invention provides clear and definite criteria by which the
blanching and destruction of normal skin tissues and normal pigment
containing cells is largely avoided, with the added consequence that the
typical whitening and abnormal skin appearance is generally eliminated as
a concomitant result.
6. The present treatment method also avoids and eliminates large-scale
destruction of the chosen treatment site and the surrounding normal cells
and tissues. Immediately following laser irradiation. The focal craters
usually formed in the stratum corneum and/or epidermis at each irradiated
site, the exudation of tissue fluid from these sites, and the crusting as
well as the blistering, are all avoided by this treatment method.
Therefore, the potential of developing infection of the treated site,
which can also potentially enhance scar formation, is further avoided.
Moreover, because the tissue injury being induced by this method is
specifically restricted and confined to the pigment containing lesion,
there is no change in skin texture from being smooth to "bumpy" or even
pitted. Similarly, there are no cosmetically disfiguring scars when the
methodology is performed in its preferred format.
7. Another major advantage of the present treatment method is that the
epidermis in the irradiated area of skin remains intact. This not only
decreases the potential risk of infection but also simplifies the
management of post-operative wound care. Moreover, because the skin
surface is intact and the treated skin area does not exude serum from the
site to form crusts, this reduces the need to protect the treated skin
with dressings for several weeks. Instead, the treated skin area need only
be protected for between 2-7 days. Finally, because the skin surface
remains intact, the possibility of the patient infecting the health care
professional through skin structures containing infected viral particles
or through infected exudate such as blood or serum are minimized.
In order to provide an accurate, comprehensive, and easily understood
description generally and in detail of the present treatment methodology,
it is both useful and convenient to focus periodically on a single
application or emphasize a particular usage in order to illustrate
specific points for the method. It will be expressly recognized and
understood, however, that all such focused or emphasized description is
also expressly representative and illustrative of the other intended
applications, usages and treatments generally, and especially those listed
within Table 1 previously herein; and that a focused disclosure in detail
is merely one instance and setting of the broad scope of treatment
applications encompassed by this method for use by dermatologists and
clinicians generally. With this understanding in mind and to achieve this
goal, the detailed disclosure will be presented in the following format
and sequence: a description of the laser apparatus, hardware
modifications, and operation parameters which are necessary for the
successful treatment and removal of pigment containing lesions; a
description of treatment details important for general clinical use and
application; a step-by-step protocol for treatment use by the
dermatologist or clinician; and a presentation of multiple case histories
of treatment with human subjects for the removal of various kinds of
pigment containing lesions in accordance with the present invention.
I. Laser Apparatus, Hardware Modifications, and Critical Laser Parameters
Since a useful description of laser apparatus will require a familiarity
and understanding of laser equipment generally, its capabilities, and the
terminology conventionally understood by laser engineers, a set of defined
terms and use conditions are provided hereinafter in order to facilitate
comprehension and depth of understanding.
Definitions
Pigment containing lesion (PCL): The presence of cells or organelles
containing pigment in concentrates which are either significantly greater
or when clustered together appear darker than normal. This makes the skin
containing this collection of "pigment" appear darker compared to
surrounding normal adjacent skin. Moreover, these pigment containing
cells/organelles could be located in areas which, under normal
circumstances, do not contain these cells/organelles such as the dermis.
Clearance: A value of the laser's ability to disrupt and remove a
sufficient amount of dye, ink, or other pigments and to return a pigmented
area of skin to near normal appearance as determined by visual inspection
and/or photography.
Lightening: An evaluation of the laser's ability to disrupt and remove a
sufficient amount of dye, ink, or other pigments and to return a pigmented
area of skin to near normal appearance as determined by visual inspection
and/or photography.
Wavelength: The frequency of the light energy with respect to the spectrum.
Wavelengths of radiation in or near the visible region are expressed
variously in Angstroms, micrometers, and nanometers. For the present
treatment methodology, the wavelengths of light delivered by the laser are
limited to the range from 700-1,100 nanometers.
Pulse Duration: The time interval (typically measures in nanoseconds) over
which the laser light beam strikes the chosen treatment site on the skin
of the living human. For purposes of the present treatment method, the
pulse duration is limited to the range of about 1-300 nanoseconds.
Fluence: The energy density provided by the light beam as applied to the
chosen or targeted treatment site on the skin of the living human. The
energy density is measured with respect to the surface area and is stated
in units of Joules per square centimeter or "J/cm.sup.2 ". The present
treatment method intends that a range of fluence from about 1-50 Joules
per square centimeter be available for use with the concomitant capability
to gradually and incrementally increase the energy density from 1 to 50
Joules per square centimeter at will or as needed.
Spot Size: The size or area of the chosen or targeted treatment site on the
skin of the individual human which is measured in millimeters of diameter.
The intended spot size can range from about 1-100 millimeters in diameter
with a preferred range of from 1-8 millimeter diameter in most instances
initially.
Peak and Average Power: The total amount of energy available from the laser
head as determined by the engineering specifications and capabilities of
the laser design. For purposes of the present treatment methodology, a
peak power of from 5-50 megawatts from the laser head is desirable. A
repetition rate of up to 5 Hz is desirable, allowing for an average power
of up to 5 watts.
Delivery System: The physical means for delivering the beam of laser light
from the laser apparatus to the chosen or targeted treatment site on the
skin of the living human patient. This term includes all necessary or
desirable equipment, controls, and engineering needed to provide the laser
operating parameters critical for successful treatment.
The Preferred Laser Apparatus
The preferred laser apparatus is an Alexandrite laser in the Q-switched
mode which provides laser pulses in a time duration in the rage of 1-300
nanoseconds; light wavelengths in the red range of the electromagnetic
spectrum of about 700-1,100 nanometers; a system for delivering the laser
light beam from the laser apparatus to the chosen or targeted treatment
site on the skin of the living patient; and, preferably, a handpiece
attached to the delivery system for controlling the delivery of the light
beam from the laser system to the chosen treatment site on the skin of the
patient with a spot size which is variable and ranges from 1-100
millimeters in diameter. The human case histories presented subsequently
herein and the individual treatments described there were performed using
the Alexandrite laser system provided by Candela Laser Corporation
(Wayland, Mass.). The minimal Alexandrite laser apparatus was then
modified as described herein to meet the critical conditions and operating
parameters required by the present treatment methodology. Although any
number of different laser apparatus and systems potentially can be
modified in principle and in design to provide the necessary parameters
and conditions required for use within the present treatment method, it is
the individual modifications of the Alexandrite laser and delivery system
which are described in detail herein as the representative apparatus
preferably used to perform the therapeutic treatment.
The typical Alexandrite laser delivery system is shown in FIGS. 1 and 2.
The apparatus 10 comprises a laser head 12, a high voltage power supply
14, a distilled water circulator (not shown), a control system 16, and a
delivery system 18. The laser head contains the cavity mirrors, Pockel's
cell, solid-state laser medium (the Alexandrite rod), and two high
intensity xenon flashlamps which excite the laser medium. Also
incorporated in the laser head is a low power continuous wave red
helium-neon laser. The outputs of the Alexandrite and helium-neon lasers
are directed into optical components which combine and focus the laser
radiation into the delivery system 18.
The delivery system 18 consist of a flexible light guide 20 with a
handpiece 22 at its distal end 24. The handpiece 22 incorporates a
distance gauge 26 which is placed against the skin of the person to ensure
proper focusing of the laser beam on the chosen area of treatment. The
output of the red helium-neon laser serves to locate the focal point 28 of
the handpiece on the skin; and a footswitch (not shown) is then used to
deliver a focused pulse of Alexandrite laser radiation to the chosen
treatment site targeted by the helium-neon laser.
The high voltage power supply charges a set of storage capacitors which
provide energy to the flashlamps. Depressing the footswitch initiates a
trigger pulse which causes the capacitors to discharge through the
flashlamps. The resulting flash excites the Alexandrite rod, causing the
emission of a pulse of laser energy. The energy of the pulse is determined
by the energy stored by the capacitors. A low power DC discharge is
maintained in the lamps between pulses by a simmer circuit.
The temperature of the Alexandrite rod must be controlled for efficient
lasing to be achieved. Circulation of heated, distilled water around the
rod regulates the temperature and also serves to cool the flashlamps. The
circulator unit which pumps the heated water through the flashlamp/rod
assembly ahs a reservoir that is maintained at the desired temperature. A
display on the circulator allows the temperature of the water to be
monitored.
The physician controls the fluence (energy density) using a 10-turn knob on
the control panel of the high voltage power supply to select the voltage
on the capacitors. This control panel is also used to enable or disable
the triggering of the laser (by turning on or off the high voltage
inverter), and to start the flashlamp simmer current prior to triggering
the laser.
The Alexandrite laser apparatus is desirably equipped with interlocks that
turn off the high voltage power supply to prevent lasing when the cover of
the laser head is opened or when the distilled water level in the
circulator reservior is low. Representative apparatus specifications are
provided by Table 2 below.
TABLE 2
______________________________________
APPARATUS SPECIFICATIONS
______________________________________
Laser Type: Flashlamp excited
Alexandrite laser
Wavelength: 700-1,100 nm .+-. 10 nm
Method of Optical Output:
Lens coupled light guide,
articulating arm or optical
fiber
Mode of Output: Multimode
Operating Mode: Single pulse operation
Maximum Delivered Output Energy:
1-50 Joules/pulse
Spot Size: 1-100 mm
Pulse Characteristic:
Rate: Single pulse (1.0 Hz
maximum)
Duration: 1-300 nanoseconds
Energy Source: Flashlamps
______________________________________
II. Hardware Modifications and Laser Operating Parameters
Certain laser operating parameters are critical for the successful
treatment of pigment containing lesions. These include:
a. a pulse duration (exposure time) in the one to hundreds of nanoseconds
range (1-300 nanoseconds);
b. a light wavelength in the red range of the electromagnetic spectrum
(700-1,100 nm);
c. average power of 1-20 watts from the laser head;
d. a delivery system for delivering the laser light from the laser to the
patient which might take the form of a light-guide, articulating arm, or
an optical fiber; and
e. a handpiece for delivery of the laser light from the delivery system
which can be placed at fixed distances from the skin surface of the
patient to ensure that spot size ranging from 1-100 mm in diameter are
being delivered.
III. General Treatment Procedures and Preferred Details
A wide variety of different pigmentations, normal and abnormal, can be
successfully treated using the Q-switched Alexandrite laser. The pigment
colors which respond best are black and blue. However, green, red, and
purple have also been effectively removed.
The Alexandrite laser apparatus should be Q-switched to provide pulse
durations of from 1-300 nanoseconds, and preferably between 50-200
nanoseconds. The spot size of the laser beam ranges between 1-100
millimeters in diameter and desirably is from 3-5 millimeters in diameter.
The light wavelength should desirably be around 760 nanometers. The energy
densities used for irradiation treatment should begin in the range from
2.0 to 10.0 Joules per square centimeter, but may be 1-50 Joules per
square centimeter on any occasion or as the individual's needs demand.
Specific pigmentation colors of the particular lesion (i.e., black, blue,
etc.) should be identified, localized, and nominated as test sites.
Specific energy densities (Joules per square centimer) used as test energy
densities should be chosen and used to treat these small areas of the
pigment containing lesion as initial test sites. The skin should either be
grayish-white and even slightly reddened immediately following laser
exposure of that test area. If the skin retains its normal skin tone after
the laser exposure, then the energy density or fluence should be increased
by 0.5-1.0 Joules per square centimeter until the skin surface becomes
grayish-white and reddened and swollen. This change in skin color should
occur immediately (up to ten minutes) after laser exposure.
The skin surface (epidermis) should remain intact. If the laser dose is too
high, blisters or punctured holes in the stratum corneum or skin surface
will appear. This will be accompanied by redness and swelling of the
surrounding area at each of the laser irradiated sites will be evident.
The laser exposed site should be protected from being traumatized by the
application of a small non-adherent dressing. The patient should be asked
to return for the next treatment visit at any time between one to ten
weeks afterwards for evaluation of the irradiated test site.
At the second or subsequent visit, the test skin area previously irradiated
is assessed for:
(a) meaningful color changes (i.e., lightening, clearance, or no change) of
the laser treated site. A notation should also be made of the color of the
immediately adjacent normal skin color;
(b) a skin texture change (i.e., elasticity, rigidity of the skin);
(c) a change in surface skin markings (i.e., the normal surface ridges and
valleys of the skin disappear when scarring occurs); and
(d) the presence or absence of adnexae (skin appendages) such as hairs
before and after irradiation.
The laser exposed skin color as well as the color change(s) in the pigment
containing lesion itself should be carefully examined and compared to
adjacent normal and non-treated skin color. If the skin color in the laser
treated area appears abnormal (procelain white, gray, or mottled brown)
compared to untreated normal skin color, this suggests that the dose used
for the first treatment is too high. By contrast, if the treated area
remains totally unchanged, then insufficient laser energy has been
delivered to the pigment containing lesion. In addition, the treated
lesion skin site should feel as elastic and mobile as the normal untreated
adjacent skin.
The goal of the treatment methodology is to lighten and eventually clear
the pigment containing lesion with successive and repeated laser
treatments, and at the same time, leave the surrounding normal skin intact
and unaffected. However, if no change in the color of the pigment
containing lesion at the test site has been noted at the first return
visit, then an additional test area and test irradiation should be
performed at a higher laser dose (by increasing the energy density of the
light beam by 0.5-1.0 Joules per square centimeter). The same process of
test site pigmentation assessment should be performed again as outlined
above subsequently at between one to ten weeks following laser
irradiation. Evaluation of test sites should continue to be performed
using increasing energy densities until substantial lightening and/or
clearance of the test site pigmentation lesion is achieved.
Note carefully, however, if one or more significant changes in the skin
comprising any of the features outlined above are observed, then the
energy density should be decreased and additional test site assessments
should be performed until the "ideal" treatment dose (i.e., the minimum
laser fluence required to produce lightening and/or clearance) is
achieved.
Once the correct fluence has been determined (i.e., the best energy density
and timed exposure producing lightening of the skin pigmentation with
minimal alteration to normal skin)--that fluence should be used to treat a
large area of the pigment containing lesion of the same color in that
individual. Following this practice, separate skin areas, section by
section, of the pigment containing lesion are then repeatedly irradiated
individually on multiple occasions until the entirety of the lesion has
been removed.
IV. Step-by-Step Preferred Protocol for Treatment
The following protocol is provided as the best procedure presently
available for the removal of pigment containing lesions. It will be
clearly recognized and understood, however, that this preferred protocol
is but a model format for many others which would vary in some details but
which retain the essential and critical features of the methodology
generally.
History and Examination
A careful history should be taken to establish when and how the pigment
containing lesion occurred on the skin of the patient. In addition, it
should be established whether other treatment modalities have been used at
any time previously in an attempt to remove the pigment containing lesion.
Details of the prior treatment and the modalities used should be
documented.
Examination should consist of a description of the actual size of the
lesion, the "colors" or type of pigmentation presented, the presence or
absence of any abnormal skin textures or typography including scars or
other abnormal pigmentation which are present. Photographs should
desirably be taken of the pigment containing lesion prior to irradiation
treatment and at each subsequent visit and irradiation treatment session.
Treatment Protocol
Two to three small areas (approximately 1-3 square centimeters of each
pigmented color, if appropriate) should be delineated. These will be
designated as the test site areas. Several test doses (e.g., 2.5, 3.0,
4.0, 5 or 6 Joules per square centimeter) should be used to irradiate each
of the different test sites. The skin should turn white/gray immediately
or within ten minutes following laser light exposure. If the pigment
containing lesion remains unchanged in color when fluences greater than 6
J/cm.sup.2 are delivered, the laser output should be checked using an
energy meter. If the output is correct, then a slightly higher fluence
will be required. One should increase the fluence only by about 0.5 Joules
per square centimeter as necessary and look out for the development of
whitening/graying on the irradiated skin. If necessary, fluences of 10-50
J/cm.sup.2 may be employed. The typical fluence to be used for the test
site should initially be less than 5 or 6 J/cm.sup.2 at a spot size of 3-5
millimeters in diameter. Care should be taken that the epidermis at the
treatment site remains intact after the irradiation exposure dose.
Following skin irradiation, a topical antibiotic ointment is preferably
applied to the treated site and the skin area protected using a
non-adherent dressing. Such topical antibiotic ointments include
Bacitracin, Neosporin, Polysporin, and Sulphadene. Alternatively, a
topical cream such as Vitamin E cream may be used in place of the
antibiotic ointment. Daily applications of the topical antibiotic ointment
and dressings to the treated site should be advocated for approximately
one week or until such time as the discoloration on the skin disappears.
The patient should be scheduled to return anytime between one and ten weeks
afterwards for subsequent evaluation of pigmented color change, i.e.,
lightening of the pigment containing lesion with minimal change in normal
skin color and any alternations in skin texture. A preferred time interval
for the return visit is between 3-7 weeks. If the laser irradiated test
site appears lightened at the return visit, the lowest dose (fluence)
producing the best lightening of the skin should be used to irradiate the
same pigmented area again as well as other areas of the lesion having the
same color using the same laser fluence and pulse duration as before.
However, if one or more of the test sites have been unresponsive to the
initial laser test dose, a higher fluence (increased preferably 0.5-1.0
Joules per square centimeter) should be used at other test sites.
The same regimen of repeated irradiations over multiple visits should be
instituted and completed until a satisfactory dose producing lightening of
the skin lesion sites is established. If no change is observed at the
different test sites following one or more exposure using fluences of 5 to
10 Joules per square centimeters, then it is likely that the particular
color in the lesion will be unresponsive to this laser.
Once a satisfactory laser fluence and irradiation exposure has been
determined, different sections of the pigment containing lesions(s) are
then separately irradiated. Those treated skin areas which have lightened
in meaningful degree following laser exposure should be irradiated again
at one to ten week intervals repeatedly. It is likely that it will be
necessary to increase the laser fluence periodically to remove the
remnants of the pigmentation as it decreases in size and color.
Irradiation of the entire pigment containing lesion section by section,
should be repeated until the lesion pigments are completely cleared. In
order to achieve this, it may be necessary t increase the laser fluence to
as much as 20-50 Joules per square centimeter on subsequent visits
repeatedly.
V. Human Case Reports
To demonstrate and empirically illustrate both the range and variety of
pigment containing lesions efficaciously treated using the present
methodology, a series of case history reports using human patients are
provided. Moreover, merely as a demonstrative aid and as a representative
showing of the many different applications intended for the present
invention, three different kinds of pigment containing lesions are
presented and summarized.
A. Treatment of benign cutaneous pigmented lesions
Case History No. 1
A 20 year old white caucasian female with a large cafe au lait (CAL)
extending from her right thigh to her mid calf was tested at 3.0 and 4.0
J/cm.sup.2 using the q-switched Alexandrite laser (760 nm) at a spotsize
diameter of 3 mm and a pulse duration of 100 nsec. There was slight
decrease in pigment at the treated sites when they were examined 6-8 weeks
after the initial laser exposure. The same area was retreated at 6.0
J/cm.sup.2 using the q-switched Alexandrite. Eight to nine weeks later,
the Alexandrite laser treated areas were lighter than the adjacent areas
of untreated CAL. New areas of untreated CAL were treated using the
Alexandrite laser at 3.0 and 4.0 J/cm.sup.2. These produced lightening of
the birthmark when the patient returned for follow-up approximately 6
weeks later. Further treatments were delivered to lighten/clear the CAL
using fluences of between 2.5 and 4.5 J/cm.sup.2 at 760 nm. All of the
treated areas lightened following laser irradiation.
Case History No. 2
The patient was a 32 year old female with a cafe au lait (CAL) on her left
back. Three test sites were exposed to 3.5 J/cm.sup.2 at 760 nm, 100 nsec,
3 mm diameter spotsize. Some lightening was observed at one of the three
test sites. Two of the three areas were retreated using the Alexandrite
laser at between 3.5 and 6.0 J/cm.sup.2 on multiple occasions at 4-12
weekly intervals which produced substantial lightening of the CAL.
Case History No. 3
An eight year caucasian female presented herself for treatment with a large
cafe au lait (CAL) on her right thigh. A test area was retreated after six
weeks at the same fluence which produced further lightening. Because of
the size of the lesion, the CAL was divided into small sections and each
area was treated and retreated at fluences between 4.0 and 6.0 J/cm.sup.2.
Retreatments to the areas were performed at between 6 and 12 weekly
intervals. Each treatment was followed by lightening of the treated site.
Case History No. 4
A 30 year old caucasian female with a cafe au lait (CAL) on her right
buttock had two different test areas delineated. Both test areas of the
CAL were exposed to the q-switched Alexandrite laser, one at a fluence of
4.0 and the other at 5.0 J/cm.sup.2. For each test area, the pulse
duration was 100 nsec at spotsize diameter of 3 mm. No change in either
test area was observed following exposure to these fluences. A further
third test area was then exposed to the ruby laser (694 nm) at 3.0
J/cm.sup.2 (maximum fluence available), a 3 mm diameter and a pulse
duration of approximately 20 nsec. No lightening was noted at the ruby
laser irradiated site.
Because no change was noted at 5.0 J/cm.sup.2 following exposure of the CAL
to the Alexandrite laser, the whole lesion was exposed to 5.5 J/cm.sup.2.
The treated areas either lightened or cleared--"breaking up" the uniformly
macular lesion into islands of hyperpigmentation with normal skin in
between these islands when the patient was examined 6 weeks after this
laser treatment. The remnants of the CAL were treated on four further
occasions, at 6 weekly intervals between treatments, at fluences of 6.0
J/cm.sup.2 using the q-switched Alexandrite laser (760 nm) at a pulse
duration of 100 nsec and a spotsize of 3 mm diameter. The totality of
these treatments cleared the CAL, leaving normal appearing skin at the
Alexandrite laser irradiated sites.
Case History No. 5
A 24 year old caucasian female was treated who had two hyperpigmented
lesions on her left calf which had been present since birth. Clinically,
these lesions were consistent with the diagnosis of cafe au lait (CAL).
Two test areas were delineated within the lesion--one test area was
exposed to 4.0 J/cm.sup.2 and the other to 3.0 J/cm.sup.2 --each using the
Alexandrite laser at pulse durations of between 50 and 100 nsec and a
spotsize of 3 mm diameter. When she was examined six weeks after the
initial laser exposure, both test areas had lightened. Both the remaining
CAL areas were treated and retreat at a fluence of 5.0 J/cm.sup.2 at 6
weekly intervals for three further treatments. Then, five further
retreatments were delivered to the same lesions at a fluence of 6.5
J/cm.sup.2, again spaced at 6 weekly intervals. One of the five further
treatments was delivered at 7.0 J/cm.sup.2. Both the lesions were
completely cleared when she returned for a follow-up visit.
Case History No. 6
A 40 year old caucasian female with a 4 year history of melasma was tested
at 4.0 and 6.0 J/cm.sup.2 using the q-switched Alexandrite laser at a
pulse duration of 100 nsec and a spotsize of 3 mm diameter. The area
treated at 6.0 J/cm.sup.2 and retreated at intervals of between 6-9 weeks
on three separate occasions appeared lighter. Having achieved this degree
of lightening, new areas of previously untreated skin with melasma were
exposed to the same treatment protocol which also lightened the affected
skin. After each laser treatment at 6.0 J/cm.sup.2, 760 nm, 100 nsec pulse
duration and a 3 mm diameter spot size, the treated skin area lightened
substantially and the skin color more closely approximated that of normal
skin coloration.
Case History No. 7
A 24 year old caucasian female presented herself for treatment of a grayish
lesion which developed on her right shoulder following treatment using
another pulsed dye laser. The clinical diagnosis of this lesion was
post-inflammatory hyperpigmentation. The lesion was then exposed to the
q-switched Alexandrite laser (760 nm), 100 nsec 3 mm diameter spotsize, on
2 occasions spaced 5-6 weeks apart, at fluences of 6.0 J/cm.sup.2 at each
visit. After the first visit, the gray hyperpigmentation lightened
considerably. This gray discoloration completely cleared after a second
laser treatment at 6.0 J/cm.sup.2 using the Alexandrite laser at 760 nm,
at a spotsize of 3 mm diameter, and a pulse duration of 50-100 nsec.
Summary of Alexandrite Laser Treatment of Benign Cutaneous Pigmented
Lesions
The q-switched Alexandrite laser at 760 nm at pulse duration of between 50
and 100 nsec, fluences of between 2.5 and 7.0 J/cm.sup.2 and a spotsize of
3 mm diameter will effectively and selectively remove some benign
cutaneous pigmented lesions (cases 1-7). Not only is the abnormally
pigmented cutaneous lesion selectively removed but the laser irradiated
skin remains normal in color, texture, and mobility, with all the adnexae
completely left intact.
The unique effect of the Alexandrite laser treatment method on skin with
the benign cutaneous pigmented lesion is the fact that the laser
irradiated skin turns white immediately following laser exposure. In
addition to this, the epidermis remains intact. Then, a few minutes (2-10
minutes) after the laser exposure, the laser irradiated area becomes
erythematous, elevated and edematous. By contrast, the surrounding normal
skin exposed to the same laser parameters as those used to treat the
benign cutaneous pigmented lesions does not become either discolored or
edematous.
B. Treatment of Epidermal Nevus
Case History No. 8
A 25 year old caucasian female with linear bands of hyperpigmented papules
on her right shoulder and chest, right upper arm and side of her trunk
presented herself for treatment. The diagnosis was epidermal nevus. A test
area was delineated on the anterior surface of her upper arm and tested
using the Alexandrite laser (760 nm) at a pulse duration of 100 nsec. The
initial test was performed at a fluence of 2.5 J/cm.sup.2, and a spotsize
of 3 mm diameter. The epidermal nevus appeared flatter when the patient
returned at the 6 week follow-up period.
Three further areas of the lesion were then delineated. Two areas were
exposed to the Alexandrite laser at an exposure over 100 nsec. One of
these was exposed to 4.0 J/cm.sup.2, and a 3 mm diameter spotsize; the
second, to 20.0 J/cm.sup.2 and a 1 mm diameter spotsize. There was some
flattening of these two sites.
The third test area of epidermal nevus was exposed to a 50 nsec q-switched
Alexandrite laser at 30.0 J/cm.sup.2, and a 1 mm diameter spotsize; this
produced significant flattening of the epidermal nevus at 6 weeks time
following the laser exposure. Because this combination of laser parameters
[a 1 mm diameter spot size, 30 J/cm.sup.2, at 50 nsec] produced the best
clinical result, larger areas of the epidermal nevus were treated using
the Alexandrite laser at 50 nsec, 1 mm diameter spotsize at fluences of
between 25 and 30 J/cm.sup.2. Since that time, between 10 and 50 cm.sup.2
areas of the epidermal nevus have been retreated a further 2-3 times,
after which time the epidermal nevus has been completely removed and
leaving adjacent normal skin unaltered. No recurrence of the tumor has
been observed. These area were unlike those previously treated using the
CO.sub.2 laser where scar formation, loss of skin pigmentation and
recurrence of the tumor were the clinical end result.
Summary of Alexandrite Laser Treatment of Epidermal Nevus
Epidermal nevus is a benign tumor of the epidermis. One problem inherent to
the treatment of this tumor has been its recurrence several months
following removal using a variety of treatments including surgery,
dermabrasion, laser treatment in particular, the CO.sub.2 laser.
The Alexandrite laser at 760 nm, 1 mm diameter spotsize, at a pulse
duration of between 50 and 100 nsec and a fluence of between 20.00 and
30.00 J/cm.sup.2 is able to effectively and permanently remove the
epidermal nevus. There has been no evidence of recurrence of the tumor at
the Alexandrite laser irradiated sites. Multiple retreatments to the same
site are required to completely remove the epidermal tumor.
The clinical endpoint of significance is whitening of the laser irradiated
skin. Unless the laser exposed skin turns white (matching the laser
spotsize diameter) immediately after the laser exposure, the laser
treatment will have minimal to no effect on the epidermal nevus. Following
this whitening, the laser irradiated area will become erythematous and
very edematous, a few minutes after laser exposure. Within a few days, the
treated area will form very superficial "scabs" which will spontaneously
"fall off" at around five to 14 days. No scarring or loss of pigment has
resulted from the Alexandrite laser treatment of epidermal nevus (tumor)
described in case history number 8.
C. Treatment of Tattoos
Case History No. 9
A 29 year old caucasian male with a professional tattoo on his chest which
was tattooed with the words "ROCKY & ROCKY JR" using blue/black ink 9
years previously.
The Alexandrite laser was set at 760 nanometers with a pulse duration in
the 50 to 100 nanosecond pulse duration range to cover a spot size of 3
millimeters diameters at fluences (energy densities) of 2-5 Joules per
square centimeter. These operating parameters were used to treat different
zones or parts of the tattoo as test sites. It was observed that the skin
at the exposed test sites, including the hairs, turned grayish-white
immediately after laser irradiation. This was accompanied by the apparent
disappearance of the tattoo from the laser exposed site. The surface of
the skin (i.e., the stratum corneum) remained intact and the skin surface
did not perforate (burst open) immediately following laser exposure.
Within 5 minutes of laser exposure, the grayish/whitening which was present
on the surface disappeared and the tattoo reappeared at the laser exposed
site. Accompanying this reappearance, the laser irradiated site appeared
"swollen" (edematous) and reddened.
At the four week follow-up visit, a thorough examination of the irradiated
test skin area was made. No significant color change in the laser treated
tattoo sites were observed. Another test site was delineated and exposed
to 5 J/cm.sup.2 using a 3 mm diameter spotsize. The exposed test skin site
again turned grayish-white immediately after irradiation when then again
disappeared from the treated skin surface about 5 minutes afterwards. The
patient was then asked to return three weeks later for the next repeat
visit.
At this subsequent three week visit, clearance of the tattoo treated
previously at 5 J/cm.sup.2 was noted. In addition, the laser treated
exposed site appeared slightly lighter than normal skin. Because there
were still remnants of tattoo at the treated site, the same skin area was
again treated using a fluence of 4 J/cm.sup.2. Section by section
irradiations of the entire tattoo were then begun.
The tattoo sections responded with lightening to irradiations of 4 and 5
Joules per square centimeter on the initial occasion. Repeat irradiation
treatments were then delivered to the same tattoo sections using these
same fluences at time intervals ranging between two and six weeks.
The tattoo became lightened with each successive irradiation treatment in
sequence, eventually clearing the entirety of the tattoo. The skin at the
treated sites retained its normal skin color as well as its normal skin
markings and elasticity throughout the irradiation treatment regimen.
Case History No. 10
A 34 year old caucasian male had multiple professional tattoos of several
color (green, red, yellow, black, and orange) of 18 years' age on both his
arms.
The patient stated that several colors had faded in the first two years
after the tattoo was placed. The yellow color faded first followed by the
fading of orange and red. At the time of initial treatment, the tattoo was
blue-black in appearance.
The Alexandrite laser was used to test the effects of irradiating the green
and black sections of the tattoo using fluences of 2, 4, and 5 J/cm.sup.2
respectively. The initial response immediately following laser exposure
was that the irradiated skin surface turned grayish-white. This was
accompanied by swelling of each test site within 1-5 minutes of laser
exposure. The grayish-white discoloration appeared over the next 5-10
minutes, after which time the tattoo reappeared and the laser exposed
sites remained swollen. The time taken for the whitening/graying to
disappear after which time the tattoo reappeared and the laser exposed
sites remained swollen. The time taken for the whitening/graying to
disappear after laser exposure was longer at the higher fluences, taking
up to 20 minutes to disappear.
The best response with lightening was achieved using 4 and 5 Joules per
square centimeter on the blue/black tattoo sections at an exposure time of
50-100 nsec. These skin areas have been repeatedly irradiated using the
same energy densities and exposure time. Lightening of the tattoo
continued with each irradiation treatment in series. In addition, some
sections of the tattoo have already been cleaned of pigment leaving the
skin at the irradiated site normal both in color and texture.
Treatment of the tattoo, section by section, is presently continuing. It is
likely that it will be necessary periodically to increase the energy
density (possibly up to 20 Joules per square centimeter) as the treatment
program progresses, and as the tattoo pigment decreases in amount, and as
the pigment aggregates fragment into smaller particles. It is expected
that each skin section may require up to 15 or 20 repeat irradiation
treatments to become completely cleared of the tattoo. A major benefit to
the patient of this procedure is that the cleared skin in the treatment
sections is indistinguishable from the normal adjacent, non-tattooed, skin
in that person.
Case History No. 11
Amateur tattoos on both arms, on the back of the right hand, and on all
four fingers and chest were created 37 and 40 years ago using Indian ink
in a caucasian male now 53 years old. The index, middle, and fourth
fingers were designated as the initial test sites. The treatment doses and
lasers used as well as the follow-up treatments are outlined in Table 3
below.
TABLE 3
______________________________________
FLUENCES USED TO TREAT INDIVIDUAL TATTOOS
IN CASE HISTORY NO. 3*
Date Index Middle Ring Fifth Hand
______________________________________
3/05 4 J/cm.sup.2
N/A 5 J/cm.sup.2
N/A N/A
3/26 5 J/cm.sup.2
5 J/cm.sup.2
5 J/cm.sup.2
5 J/cm.sup.2
5 J/cm.sup.2
4/14 4 J/cm.sup.2
4 J/cm.sup.2
4 J/cm.sup.2
4 J/cm.sup.2
4 J/cm.sup.2
5/14 5 J/cm.sup.2
5 J/cm.sup.2
5 J/cm.sup.2
5 J/cm.sup.2
5 J/cm.sup.2
______________________________________
*Other laser parameters remained constant.
Spot size = 3 mm diamters.
Pulse duration = 50-100 nsec.
Wavelength = 760 nm.
N/A = not attempted.
The tattoos at these individual sites lightened with each irradiation
exposure except those skin areas irradiated on the initial visit of 3/05.
The fluences employed on that occasion were varied to determine how
differences in laser energy density would affect the degree of lightening
achieved.
On the initial visit of 3/05, the treated skin turned grayish-white
immediately after laser exposure at both 4 and 5 J/cm.sup.2 respectively.
Then, about 5-7 minutes after irradiation, the grayish-white coloration
was replaced by the return of the pigmented tattoo at each of the treated
test sites.
At the return visit of 3/26, very little change was seen in the previously
irradiated skin sites and the laser fluence used on 3/05 was then
increased by 1 J/cm.sup.2, while keeping the other laser operating
parameters constant. Again, the skin sites irradiated on this occasion
turned grayish-white immediately after laser exposure. The patient was
then asked to return in 20 days time for the next visit.
At the follow up visit of 4/14, a few areas of the previously irradiated
skin appeared slightly lighter than the adjacent non-tattooed normal skin.
Therefore, the laser fluence was decreased to 4 J/cm.sup.2 using and
exposure time of 50-100 nsec and a spot size of 3 mm in diameter. After
treatment, the patient was to return in 30 days for his next visit.
On the visit of 5/14, however, very little change in color was observed at
those skin sites irradiated on 4/14 using the 4 J/cm.sup.2 energy density.
Therefore, the fluence was again increased to 5 J/cm.sup.2 while the other
operating parameters of exposure time, spot size, and light wavelength
remained the same. Treatment of the tattoo, section by section, was then
begun.
It is expected that increases in laser fluence up to 20 J/cm.sup.2 will be
required to clear the tattoo entirely as it lightens in color. Also, it is
likely that multiple treatments involving up to 20 return visits will be
needed at intervals of 2-10 weeks between each irradiation treatment in
order to complete this regime.
Case History No. 12
An amateur tattoo with the words "JOHN" on the left outer thigh of a of a
33 year old caucasian female was created 13 to 14 years ago using blue
Indian ink. The whole lesion, which was approximately 1.5.times.3.0 cm,
was exposed to light from the Alexandrite laser at 760 nm, 50-100 nsec
exposure time, 3 mm diameter spotsize, and a fluence of 5 J/cm.sup.2. The
skin immediately following laser exposure turned grayish-white, this
coloration gradually disappearing after 5-10 minutes and after which the
treated sites appeared swollen, raised, and pink. When the tattoo was
examined at the second visit sex weeks following the initial treatment,
the whole tattoo had lightened and thus was retreated using the same laser
operating parameters. Laser exposures of the tattoo now continue with
return visits for treatment scheduled between to and eight week intervals
and with increasing irradiation fluence until the whole tattoo clears
completely. It is expected that between 8 and 12 treatments will be
required to completely clear the tattoo.
Case History No. 13
A professional tattoo formed as two hands clasped together was placed 30
years ago on the right forearm of a caucasian male now 47 years old. The
right side of the tattoo was purposely exposed to laser light from the
conventional ruby laser while the left side of the tattoo was exposed to
laser light from the Alexandrite laser. The operating parameters of both
laser irradiations were similar; each irradiation used a fluence of 4
J/cm.sup.2 and an exposure time of 50-100 nsec.
At the first return visit 4 weeks later, the patient reported that the
right side of the tattoos exposed to the ruby laser oozed shortly after
initial irradiation; and that the oozing was replaced by crusts on the
skin surface within 1-2 days of treatment. The skin crusts persisted for
nearly two weeks and then gradually fell off leaving the skin area
"whiter" than the normal adjacent skin. By the time of this first return
visit (4 weeks after initial irradiation), a lightening of both the right
and left sides of the tattoo was observed.
The treatment procedure was then purposely repeated on this first return
visit; the right and left sides of the tattoo were again irradiated
individually using the ruby laser and Alexandrite laser and the same
operating parameter as on the initial treatment occasion. The patient was
then asked to return after four additional weeks for his next visit.
On the third visit (8 weeks after the initial treatment), the right side of
the tattoo exposed to the ruby laser appeared more hypopigmented--that is,
whiter in color and more shiny in appearance--than the left side of the
tattoo irradiated previously using Alexandrite laser light. In addition,
the skin on the Alexandrite laser treated left side was not only
completely cleared of the tattoo but also appeared normal both in skin
color and skin texture with respect to the untreated skin areas
immediately adjacent. However, the Alexandrite laser treated skin was
substantially different and in marked contrast to the ruby laser exposed
skin which demonstrated a potentially permanent loss of normal skin
pigmentation as a consequence of irradiation.
It is of major significance that the left side of the tattoo irradiated
with the Alexandrite laser light has apparently cleared completely after
only two irradiation treatment occasions; and has left the treated skin
area of the patient in a normal condition as to both coloration and
texture. It is also noteworthy that the Alexandrite laser treated skin did
not cause any oozing of the skin tissue; did not become crusty or hard as
a consequence of the irradiation; and did not become either hypopigmented
or scarred.
The remainder of the tattoo of the patient will now be treated section by
section using only Alexandrite laser light under the earlier described
operating parameters. Treatment visits will be scheduled repeatedly at 2-8
week time intervals with increasing irradiation fluence if necessary until
the entirety of the tattoo is completely cleared. It is expected that
approximately 10-15 treatment occasions will be required to achieve
complete clearance of the entire tattoo.
Case History No. 14
A 42 year old caucasian male had a panther professionally tattooed on his
upper arm 25 years earlier. Most of the tattoo was outlined and filled in
with blue/black in. The tip of the panther was irradiated using a fluence
of 2.5 Joules per square centimeter for 50-100 nsec using the Q-switched
Alexandrite laser while another part of the tail was irradiated using the
ruby laser with light at 694 nanometers using fluences of 2.0 and 3.5
Joules per square centimeter for the same time exposure. On the return
visit, approximately six weeks later, very little change was observed on
the skin at the Alexandrite laser irradiated area but some lightening of
the skin was observed at the ruby laser irradiated site. At this return
visit also, the right leg and lower half of the body of the panther tattoo
was exposed to light from the Alexandrite tattoo was exposed to light from
the Alexandrite laser at a fluence of 4 Joules per square centimeter while
the left leg of the panther tattoo was exposed to the ruby laser at a
fluence of 4 Joules per square centimeter, both irradiations being of
50-100 nsec exposure time. The patient was then scheduled to return in 4
weeks.
On the occasion of his third visit, a direct comparison of the ruby laser
treated skin and the Alexandrite laser irradiated skin was made in detail.
Significant lightening was observed at all the treated skin sites.
However, areas treated using the ruby laser had punctuate openings at the
surface of each site through which oozed blood and serum. These areas
subsequently crusted over; some of this crusting was still evident after
ten weeks. By contrast, the skin remained intact at every site exposed to
the Alexandrite laser in spite of the fact that the skin turned a grayish
white immediately after laser irradiation on each occasion.
Another difference noted at the third visit was the fact that the ruby
laser irradiated site appeared hypopigmented compared to the Alexandrite
irradiated sites. These findings suggest that the Alexandrite laser beam
penetrated deeper into the skin than the ruby laser beam. Therefore,
because the tattoo pigment most often "aggregates" around dermal vessels
in the papillary dermis, the Alexandrite is a more efficient laser for
destroying pigment than the ruby laser. This is because some of the ruby
laser's energy will be lost through absorption by more superficial
cutaneous structures such as stratum corneum and epidermis. When this
happens, very little energy will be left for absorption by structures in
the dermis. Moreover, it is evident that short pulses at high powers are
needed to fragment dermal tattoo pigment. Because the ruby laser will have
lost some of its energy at the surface, it will be less efficient at
breaking up the tattoo fragment in the dermis. In order to be able to
break up the tattoo pigment, higher doses will be required; and when high
doses are used, then more damage will be induced at the skin surface. This
damage consequently will heal by scar formation.
This tattoo will now be treated using increasing doses of Alexandrite laser
light alone at two to eight weekly intervals for an expected 15-20
treatment visits at which time the tattoo will be completely cleared.
The present invention is not to be restricted in form nor limited in scope
except by the claims appended hereto.
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